The invention discloses a snowballing type character searching method. For a binary image, an overall character can be found out step by step by starting with a pixel point in a license plate character region. According to the license plate image extraction method, vehicle image binaryzation is carried out; whether a license plate character has a white color is determined by using a snowballing type character searching method; if not, inverse processing is carried out. With a maximum value of a horizontal projection of a vertical edge and a vertical projection of a horizontal edge, one point in the license plate image is determined; an upper boundary line, a lower boundary line, and a right boundary line of a character region are found out step by step by using the snowballing type character searching method; and according to the dimension of the found character and a distribution characteristic of the character on the license plate, a left boundary of the character region can be found based on column-by-column searching.